My fiance and I have spent our last two weekends priming ceilings. It's hard work, but rewarding. Every night after a few hours' work, we fastidiously clean out the rollers and brushes, using more water than we'd like—and they're never up to par the next day. This was our practice until a friend stopped by today and let us in on a painter's secret. To make the rollers and brushes last much, much longer (and save gallons of water in the meantime!), here's what our friend told us:
After you're done painting for the day, wrap the roller or paintbrush in a wet towel. Place it in a plastic bag or wrap it with plastic wrap, and then—here's the secret—put it in the fridge. The roller or brush will stay fresh until you're ready to paint again!
This will make the roller last quite a bit longer and keeps cleanup to a minimum. You'll spend less money on supplies, and use many fewer resources. Sounds like a green dream come true.